BigBattery Golf Cart 42.9v LiFePO4 and 600A Navitas on 2014 Ezgo RXV
 

Hi All, hoping I am able to provide my experience with this battery and get some advice/ help along the way.

I posted my setup in this thread along with pictures, i can copy it back here if that is preferred?

https://www.buggiesgonewild.com/show...6&postcount=24

and

https://www.buggiesgonewild.com/show...0&postcount=25

The top level issue i have:

Navitas 600 controller expects a 48v lead acid system, so will shut down when the voltage gets to about 41-42V. This BigBattery is rated 35V to 46.8V so Navitas cuts my useable power worse than a lead acid would at 50%.

Navitas can be set to 36v mode, but then it thinks the battery is too full, so starts dumping amps to the resistor coil, and that glows a nice pink/ red :) And i think will catch fire if i left it.

Navitas state they are working on updating their firmware to support me, and the lithium community, but what they expected would take 7-10 days is now 5+ weeks. I dont mind waiting, lots of rain in Florida right now, and i have had chance to do some other upgrades to the cart, and i feel grateful they will fix this for me. BUT - i dont want to be stuck here until Christmas still waiting.

I have my old Curtis controller, can that be re-programmed to work with this battery/ operate within its conditions? <This is my real question.

Please tell me if there are any specifics i need to post about the navitas controller or the curtis i will jump on that.

I've read so many posts on this forum over the years and its really helped me just being an observer, so big thank you in advance for any help anyone can offer.

Re: BigBattery Golf Cart 42.9v LiFePO4 and 600A Navitas on 2014 Ezgo RXV
 

Your best bet is unfortunately to wait for the Navitas software update that will give you a "range" instead of fixed voltage settings for the pack voltage.

I also noticed that BMS is rated for 130 amps so that could be an issue depending on your normal outside temperature and driving habits.

Is that graph you posted showing battery amps or motor amps?

Re: BigBattery Golf Cart 42.9v LiFePO4 and 600A Navitas on 2014 Ezgo RXV
 

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Thanks Sergio. The graph was amps from the battery.

Re: BigBattery Golf Cart 42.9v LiFePO4 and 600A Navitas on 2014 Ezgo RXV
 

Another idea i had, would it even be a viable option if i made a 7.2V LF battery rated at 85 ah and placed it in series to boost the voltage up, so the controller now sees a 48v? That all seems a bit clunky to me, i'd have two seperate BMS? two chargers?

Re: BigBattery Golf Cart 42.9v LiFePO4 and 600A Navitas on 2014 Ezgo RXV
 

I have reprogrammed many RXV Curtis controllers, and I always reprogram their input voltage range to accept lithium packs. This prevents undervolt and overvolt errors, and keeps the resistor from being activated within the typical normal lithium pack range.

Re: BigBattery Golf Cart 42.9v LiFePO4 and 600A Navitas on 2014 Ezgo RXV
 

Thanks Bob. I have a question if i may, this LF battery pack spec is:

Nominal Voltage: 42.9V
Capacity: 88.59Ah (3.8kWh)
Configuration: 13S 6P
Chemistry: LiFePO4
Battery Management System: 13S BMS
Max Charge Voltage: 46.8V
End of Discharge Voltage: 35V

Would there be any issues with the RXV motor working with those voltages?

Would my original 235A curtis controller model: 1206AC-5201 be capable of being re-programmed to work with those voltage ranges? i.e. they are not too low are they?

Re: BigBattery Golf Cart 42.9v LiFePO4 and 600A Navitas on 2014 Ezgo RXV
 

No problem whatsoever once the controller has been reprogrammed for that voltage range. 3 phase AC motor stator current will rise as the pack voltage falls, but that is totally normal in order to maintain rotor lock at the lower voltage.

Yes. I always reprogram the 235 Amp controllers to accomodate common lithium packs wider voltage range.

Re: BigBattery Golf Cart 42.9v LiFePO4 and 600A Navitas on 2014 Ezgo RXV
 

Thanks Bob i had some buyer remorse concerns about the voltage, but did believe it should work, good to hear you say that for sure!

Re: BigBattery Golf Cart 42.9v LiFePO4 and 600A Navitas on 2014 Ezgo RXV
 

Last night i had an email from navitas, they are looking to update the app (i presume with a new firmware) next Tuesday/ Wednesday. Great news!

That gives me time to re-spray my white ezgo some other color...

Attachment 206035

Re: BigBattery Golf Cart 42.9v LiFePO4 and 600A Navitas on 2014 Ezgo RXV
 

Glad to hear that. I was hoping that me talking about it recently would motivate them to fix that particular item. I'm wanting to get to the point that I can fully recommend Navitas upgrades for RXV owners. It'll definitely reduce my workload of Curtis controller reprogrammings.